Abstract
Numerous glasses were prepared from mixtures of alkali halides and boron oxide and subjected to 60Co γ rays at room temperature; these were examined by ESR techniques at 9.1 and 35 GHz. The induced spectra can be divided into two categories: (1) a resonance due to boron–oxygen centers previously studied in alkali borate glasses, and (2) certain new resonances which are shown to be due to V-type centers (halogen2− molecule ions). The Cl2− species is stable at room temperature; its spin-Hamiltonian parameters determined by means of a computer simulation of the spectrum are: g‖ = 2.0042, g⊥ ≃ 2.035, A‖ = 100 G35–35, A⊥≃8 G35-35. Inclusion of small amounts of KCl or LiCl in borate glasses can result in nearly total suppression of the usual boron–oxygen-center resonance, i.e., the dissolved chloride ions prove to be the more efficient hole traps. The Br2− centers can also be formed, but less efficiently. The F2− centers are not produced in borate glasses which is consistent with other data which suggest that fluorine forms covalent bonds with boron in these materials.
Published Version
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